Pipe-threading die



* Jan. 29, 1929;

H. W. SMITH PIPE THREADING DIE Original Filed May 28, 1 923 'INVENTOR Patented Jan. 29, 1929.

UNITED S'lU t 'l'Efil HOWARD W. SMITH, 0F ELL'WOOD CITY, PENNSYLVANIA.

PIPE CEHREADING DIE.

Original application filed May This invention is a division of my application, Serial No. 641,987, which resulted in Patent No. 1,620,830 and relates to dies for threading pipe and for similar purposes, and its object is to provide an improved threading die which shall be capable of cutting long, tapered threads with the use of relatively short Chasers.

In cutting tapered pipe threads it is nec essary that the chasers in the die be at least as long, with a little to spare, as the thread that is to be cut. For very long threads it has heretofore been necessary to employ correspondingly long Chasers, and the hardening of such chasers is a difficult matter on account of the fact that they tend to change their shape. One harmful result of this, among others, is that the pitch of the thread in such a chaser is not accurate.

According to my present invention, I provide pipe-threading dies adapted for cutting long, tapered threads without the use of unusually long chasers, and in a manner which will allow any inequalities in the thread to be easily corrected. I accomplish this result by providing a ring which supports the chasers in grooves which are so arranged that short chasers may be inserted therein and will. be be held rigidly in the proper position to cut threads that are longer than the length of any one of the chasers.

In one arrangement for this purpose, I split the supporting ring-centrally and provide grooves for the chasers which extend across the ring sect-ions. In this construction, the chasers are preferably staggered. If desired, however, the split ring sections may be '50 arranged that the chaser grooves are in line with ach other, in which case the short chasers are arranged end to end with their inner ends in contact.

Another feature of my invention consists in providing fewer chasers on the back row than in the front row. The chasers do their heaviest work at the front of the die where the cut begins, and the work of cutting the rear portions of the threads may be done with only half as many chasers as are necessary in cutting the front portions of the threads. This arrangement isintended to be used only for the larger sizes of pipe and notfor smaller sizes where the total number of chasers in an ordinary die is six or less.

In the accompanying drawing, Fig. 1 is a side elevational view of a ring die supported 28, 1923, Serial Ito. 641,98'5. Divided and this 25, 1927. Serial No. 178,327.

application filed March in an expanding shell and provided with chasers arranged according to my present invention; :Fig. 2 is a vertical sectional view taken through the construction of Fig 1 and substantially on the line II-II, Fig. 1, and Fig. 3 is a vertical sectional View taken through a modified construction.

In Fig. 1 of the drawing, the numerals 2 and 3 indicate the upper and lower semi-circular halves of an expanding shell and are pivoted at one end upon pivot-bolts at connected by links 5. The expanding shell is opened and closed at the side opposite the pivot-bolts a, by means of a vertical screw 6 having right and left threads extending through screwthread openings which are formed in round pins 7 that are received in horizontal onenmgs in projections 8 at the ends of the sections 2 and 3. This arrangement permits the screw 6 to engage the pins or swiveled nuts 7, without binding, in all angular positions of the die sections, the halves of the expanding shell being free to rotate around the pins 7 whenever the dies are opened or closed. A handle 9 is secured to the upper end of the screw 6, and an auxiliary screw 10 and a nut 11 may be provided forfixing the adjusted position of the expanding shell.

Within the expanding shell is a removable ring die consisting of, two sections 12 and 12" each of which fits into its half of the expan ding shell and is removably secured therein by means of a guide pin 13 and a bolt 14. The guide pin 13, as shown in Fig. 1, is driven from the inside in a hole in the expanding shell and is riveted on the outside. The ring diesare thus readily removable.

As shown in Fig. 2, the ring die sections are provided with axiallyxtending grooves for the reception of chasers 15, and with counter-sunk grooves 16 at their edges, the latter named grooves being arranged to receive clamping plates 17 which are secured to the ring sections 12 and 12 by means of screws 18 and serve as detachable stop members to hold the chaser-s in place. as hereinafter explained, the pairs of die members 12 and 12 being respectively secured together by means of bolts 19.

The chasers 15 are received in their grooves, as above stated, with the inner ends of each circumferentially-arranged set in abutting engagement with the inner ends of the other set, and are clamped in place by means of the plates 17 and screws 18. In assembling this form of device, the clamping plates 17 are first attached to the separate portions of the ring die sections, the chasers are placed in their grooves, and the Separate portions of the die sections are secured together by means of the bolts 19, after which the clamping plates 17 are tightened by means of the screws 18, to rigidly clamp the chasers.

In the construction as shown in Fig. 3, the upper and lower sections oi the ring die are indicated by the numerals 20 and 21,, respcctively, and are split on the line 22, the separate portions of the ring die members being connected together by means of bolts 28.

Chip-grooves 2 are formed in the combined ring-die sections and short chascrs are received in slots that are formed in the chipgrooves 24. The chasers of one ring-die member abut at their inner end against the inner surface of the adjacent ring-die member. The Chasers 25 shown in Fig. 3 are somewhat shorter than the width of the ring-die sections and are held in position by means of set-screws 26, which extend through threaded openings in the clamping plates or ring sections 26. Two pairs of the set-screws 26 are shown in Fig. 3, the remaining set-screws being omitted for the sake of clearness. It will. be observed that the die shown in Fig. 3 has'ene half as many chasers on the left or back row as on the right or front row. As stated above, the chasers do their heaviest work at the front end where the cut begins and fewer chasers in the back row are with cient. The clamping plates 26 are clamped in position by means of screw-bolts 27 and serve as stop members to hold the chasers in place.

I claim as my invention:

1. Threadingdie structure comprising two coaxially mounted ring die sections each of generally annular form and provided with axially extending grooves for thread chasers, stop means at the inner side oi each die section for liii'iiting inward movement of the chasers of the other section, stop means at the outer ends of the chasers, and means for detachably secru'ing the die sections together.

2. Threading die structure comprising two co-axially mounted ring die sections each of generally annular form and provided with axially extending grooves for thread chasers, stop means at the inner side of each die section for limiting inward. movement of the chasers of the other section, detachable stop means at the outer ends of the chasers, and means for securing the die sections together.

3; Threading die structure comprising two co-axially mounted ring die sections each of generally annular form and provided with axially extending grooves for threaochasers, the grooves of one section being circumferentially offset with relation to the other sec tion, so that the inner radial face of each section will serve as a stop for the inner ends 01 the ch'asers of the adjacent section, and stop members secured to the outer radial surfaces of each of the two sections, for holding the chasers in their grooves.

4. Threading the structure comprising two co-axially mounted ring die sections each of generally annular form and provided with axially extending grooves for thread chasers, tl e grooves of one section being circumferentially offset with relation to the other section, so that the inner radial face of each section will serve as a stop for the inner ends f the chasers of the adjacent section, and stop members secured to the outer radial surfaces of each of the two sections, for holding the Chasers in their grooves, the die sec tions being provided with chip grooves, that respectively extend entirely across the inner face of one die and into the other die for a substantial distance beyond the inner end of the adjacent chaser.

5. Threading die structure, comprising two co-axially mounted ring die sections each of generally annular form and provided ith axially extending grooves for thread chasers, stop means at the inner side of each die section for the inner ends of the chasers of the other section, and means for securing the die sections together.

6. Threading die structure, comprising two co-axially mounted ring diesectioiis each of generally annular form and provided with axially extending grooves for thread chasers, one section having a greater number of grooves than the other section and having its grooves circum'terentially offset with relation to the grooves of the other section, so that the inner radial surface of each section will serve as a stop for the inner ends of the chasers of the adjacent section. V

In testimony whereof I, the aid HowAnD W. Sistrrri, have hereunto set my hand. A

HOTVARD N. SMITH. 

